1. Technical Field
The present application relates generally to perforating and more particularly to shaped charges having cases made with sintered metal powders.
2. Background Art
To complete a well for purposes of producing fluids (such as hydrocarbons) from a reservoir, or to inject fluids into the reservoir, one or more zones in the well are perforated to allow for fluid communication between the wellbore and the reservoir. Normally, perforation is accomplished by lowering a perforating gun string that has one or more perforating guns to the desired intervals within the well. Activation of the one or more guns in the perforating gun string creates openings in any surrounding casing and extends perforations into the surrounding formation.
A perforating gun typically includes a gun carrier and a number of shaped charges mounted to the gun carrier. The gun carrier can be a sealed gun carrier that contains the shaped charges and that protects the shaped charges from the external wellbore environment. Alternatively, the gun carriers can be on a strip carrier onto which capsule shaped charges are mounted. A capsule shaped charge is a shaped charge whose internal components are sealably protected against the wellbore environment.
One of the major problems facing designers of perforating guns for use in oil and gas wells may be the issue of gun survivability, especially, in guns, where charges are used in high shot densities. The causes of gun failure include the initiation of cracks on the interior gun wall caused by the impact of the shaped charge case fragments traveling at high speed and as a result of the high gas pressure generated by the explosion within the case.
Combination of the multiple impact sites and the high interior gas pressure can form centers of damages and initiate cracks in the gun wall, thereby compromising the integrity of the gun wall. Such a failure may rupture the gun and lead to costly retrieval of the destroyed gun from the well.
Another issue associated with the use of the conventional perforating guns is that the fragments, generated from the detonated cases, may damage the fluid circulation pumps or interfere with completion equipment. Furthermore, these fragments may restrict the flow of hydrocarbons through the perforations inside the wellbore casing.
Therefore, better shaped charges are needed to enhance gun survivability and protect downhole equipment.